Re: [Qemu-devel] [PATCH, RFC] ld flag --warn-common

[Blue Swirl]

On 9/22/08, Kirill A. Shutemov <address@hidden> wrote:
> On Mon, Sep 22, 2008 at 07:24:27PM +0300, Blue Swirl wrote:
>  > On 9/22/08, Kirill A. Shutemov <address@hidden> wrote:
>  > > On Sat, Sep 20, 2008 at 10:49:36AM +0300, Blue Swirl wrote:
>  > >  > On 9/19/08, Kirill A. Shutemov <address@hidden> wrote:
>  > >  > > On Sun, Sep 07, 2008 at 11:24:37AM +0300, Blue Swirl wrote:
>  > >  > >  > Hi,
>  > >  > >  >
>  > >  > >  > These trivial patches enable linker flag --warn-common and fix 
> the
>  > >  > >  > warnings caused by enabling the flag.
>  > >  > >
>  > >  > >
>  > >  > > This flag cause a lot of warning on my machine, even with trivial 
> program.
>  > >  > >
>  > >  > >  $ cat 1.c
>  > >  > >  #include <stdio.h>
>  > >  > >
>  > >  > >  int main()
>  > >  > >  {
>  > >  > >         printf("test\n");
>  > >  > >         return 0;
>  > >  > >  }
>  > >  > >  $ gcc -Wl,--warn-common -static 1.c
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtoul.o): 
> warning: multiple common of `_nl_category_name_idxs'
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): 
> warning: previous common is here
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol_l.o): 
> warning: multiple common of `_nl_category_name_idxs'
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): 
> warning: previous common is here
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtoul_l.o): 
> warning: multiple common of `_nl_category_name_idxs'
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): 
> warning: previous common is here
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(vfprintf.o): 
> warning: multiple common of `_nl_category_name_idxs'
>  > >  > >  
> /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): 
> warning: previous common is here
>  > >  > >
>  > >  > >  ...and so on.
>  > >  > >
>  > >  > >
>  > >  > >  Is it problem with my toolchain? What is your testing environment?
>  > >  >
>  > >  > I get no warnings for Qemu build on Debian i386, amd64
>  > >  > (stable/unstable), Sparc32, Sparc64 or on OpenBSD/Sparc64. Your
>  > >  > program produces one warning on Debian stable (all hosts except no
>  > >  > warnings on arm), no warnings on Debian amd64 unstable or OpenBSD.
>  > >
>  > >
>  > > I've got a lot of warnings on ALT Linux x86_64 and Ubuntu x86_64. Both
>  > >  with gcc 4.1.2. Are you sure that you test static build?
>  >
>  > $ gcc -Wl,--warn-common -static main.c
>  > /usr/lib/gcc/x86_64-linux-gnu/4.1.2/../../../../lib64/libc.a(dl-open.o):
>  > warning: definition of `_dl_tls_static_size' overriding common
>  > /usr/lib/gcc/x86_64-linux-gnu/4.1.2/../../../../lib64/libc.a(libc-tls.o):
>  > warning: common is here
>  > $ cat main.c
>  > #include <stdio.h>
>  >
>  > int main()
>  > {
>  >        printf("test\n");
>  >        return 0;
>  > }
>
>
> I think --warn-common shouldn't be added to LDFLAGS, when we build static
>  qemu.

Another solution would be to add a configure time check if the system
libraries suck or not. Though these are only warnings and you seem to
be the only person complaining.